Control receiver

ABSTRACT

A receiver comprises two mechanical resonators resonating at transmitted frequencies different from each other and two coils coupled to them respectively. At one of the frequencies, the corresponding resonator causes the mating coil to produce a voltage which is applied to a switching thyristor to rotate an AC motor. After the rotation of the motor through a predetermined angle, a switch is closed to permit the energization of the associated load while stopping the motor. At the other frequency, the remaining resonator and mating coil are similarly operated to deenergize the load. There are also disclosed means for controlling an operating time point of the switch.

United States Patent Taketa et al.

l l CONTROL RECEIVER [75] Inventors: Katsumi Taketa; Kenji Takahashi,

both of Fukuyama, Japan [73] Assignee: Mitsubishi Denki Kabushiki Kaisha,

Japan [22] Filed: Aug. 3, 1973 [2l] Appl. No.: 385,243

[30] Foreign Application Priority Data Aug, 9. 1972 Japan 47-79655 Aug. 9, l972 Japan 47-79656 [52] US. Cl. 307/129 [51] Int. Cl. H0lh 47/20 [58] Field of Search 307/l29; 3l7/l47, 138

[56] References Cited UNITED STATES PATENTS 2,534,144 12/1950 Price et al 317/138 2,641,716 6/1953 Hyer et al. r. 3l7/l38 May 27, 1975 McDonald 307/! 29 Balan 3l7/l38 8/1956 ll/l96l 2,76l,03l 3,0l L102 [57] ABSTRACT A receiver comprises two mechanical resonators resonating at transmitted frequencies different from each other and two coils coupled to them respectively. At one of the frequencies, the corresponding resonator causes the mating coil to produce a voltage which is applied to a switching thyristor to rotate an AC motor. After the rotation of the motor through a predetermined angle, a switch is closed to permit the energization of the associated load while stopping the motor. At the other frequency, the remaining resonator and mating coil are similarly operated to deenergize the load. There are also disclosed means for controlling an operating time point of the switchv 4 Claims, 4 Drawing Figures CONTROL RECEIVER BACKGROUND OF THE INVENTION This invention relates to control receivers for use with a central control system for transmitting control signals to the receivers through the associated power transmission or distribution line to simultaneously control the opening and closure of loads such as electrical water heaters provided for customers.

In central control systems utilizing control signals from the power substation to simultaneously control the opening and closure of loads provided for customers, their malfunctions due to noise and the like must be prevented while they should be inexpensive because of the use of a multiplicity of control receivers. In those central control systems, the simultaneous closure of the loads for example, electrical water heaters disposed for customers by means of the control signal transmitted from the power substation may result in a variation in system load great enough to degrade the quality of power supply.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a new and improved control receiver employed in a central control which is simple in construction, inexpensive and accurately operative with a high reliability.

It is another object of the present invention to provide new and improved control receivers for use in a central control system of the type referred to which is responsive to control signals from the system to actuate the associated switches at suitable time intervals in the area of a particular substation where the central control system is disposed.

The present invention accomplishes these objects by the provision of a control receiver comprising, in combination, a first electromagnetic coil responsive to a signal having a first predetermined frequency to produce an output thereacross, a second electromagnetic coil responsive to a signal having a second predetermined frequency different from the first frequency to produce an output thereacross, a load circuit to be controlled, switch means connected in a circuit with the load circuit and having an open position where the load circuit is maintained open with the first coil put in its closed position and a closed position where the load circuit is maintained closed with the second coil put in its closed position, a switching circuit responsive to the output from that electromagnetic coil put in its closed position by the switch means to be conducting, and means responsive to the conduction of the switching circuit to change the switch means from one to the other of the open and closed positions.

Preferably, the control receiver may comprise a signal responsive circuit responsive to the signal having either of the first and second predetermined frequencies to establish an oscillating magnetic field therein, a first mechanical resonator operatively coupled to both the signal responsive circuit and the first coil to respond to the magnetic field established in the circuit at the first frequency to cause the first coil to produce the output across the latter through the vibration thereof, and a second mechanical resonator operatively coupled to both the signal responsive circuit and the second coil to respond to the magnetic field established in the circuit at the second frequency to cause the second coil to produce the output therethrough, through the vibration thereof, the arrangement being such that the switch means responds to the output from the first coil to permit the energization of the load circuit and to the output from the second coil to cause the deenergization of the load circuit.

In order that, with a multiplicity ofthe control receivers disposed in the area of a particular power substation, the associated switch means are actuated at suitable time intervals, each of the control receivers may comprise first cam means for opening and closing the switch means, an electric motor for actuating the first cam means, a second cam means for stopping the electric motor, and adjusting means for adjusting the angular position of the first cam means relative to the second cam means to control a time interval between the reception of the control signal by the receiver and the actuation of the switch means.

BRIEF DESCRIPTION OF THE DRAWING The present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. I is a circuit diagram of a control receiver constructed in accordance with the principles of the present invention;

FIG. 2 is a diagram similar to FIG. I but illustrating a modification of the present invention;

FIG. 3 is a schematic view illustrating a mechanical connection between components 11 and 12 as schematically shown by a broken line in FIG. 2 in one adjusted position, and

FIG. 4 is a view similar to FIG. 3 but illustrating the mechanical connection in another adjusted position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and FIG. 1 in particular, it is seen that an arrangement disclosed herein comprises a pair of source terminals 15 and 2S and a pair of load terminals 1L and 2L. The source terminals are adapted to be connected to service conductors extending from a power distribution line to each customer although the conductors and line are not illustrated. The load terminals 1L and 2L are adapted to be connected across a load such as an electrical water heater (not shown) provided to the customer. The source terminal 2S is connected to the load terminal 2L through a lead while the source terminal 15 is connected to the load terminal 1L through a normally open switch 12 as will be described hereinafter.

The invention further comprises a signal responsive circuit shown as a series resonance circuit including an exciting coil 1 connected in series to a capacitor 2 across the source terminals IS and 28. The signal responsive circuit is adapted to respond to a pair of signals having different frequencies of f and f as determined by the inductance of the coil 1 and the capacitance of the capacitor 2 and therefore the circuit nearly resonate at each of those frequencies to establish an oscillating magnetic field having a relatively high amplitude. In the example illustrated, the frequencies of f, and f are selected to be on both sides of the resonance curve for the series resonance circuit 1 2 and therefore the circuit nearly resonates at each of those frequencies to establish an oscillating magnetic field hav ing a relatively high amplitude. Disposed within the magnetic field established by an alternating current flowing through the coil 1 are a pair of mechanical resonators 3 and 4 having respective natural frequencies equal to the frequencies off and j; and provided adjacent the free ends thereof with their own pickup coils 5 and 6. Thus each of the resonators 3 and 4 is responsive to the alternating current flowing through the ex citing coil 1 to vibrate to cause a change in a magnetic flux flowing through the associated magnetic circuit including a permanent magnet as a part of thereof. This causes the pickup coil operatively coupled to the vibrating resonator to develop a very low voltage thereacross.

The coils 6 and 5 are connected at one end to a gate electrode of a thyristor 7 subsequently connected to the source terminal 15 through a gate protective resis tor 8. The thyristor 7 has a cathode electrode connected to the source terminal 18 and an anode electrode and has a semiconductor diode connected across the anode and cathode electrodes thereof with a polarity reversed to that of the thyristorv The anode electrode of the thyristor 7 is further connected to a capaci tor l subsequently connected to an alternating current (AC) motor 11. The switch 12 includes a movable arm connected to the source terminal IS and a pair of stationary contacts. One of the stationary contacts 12c is connected to the pickup coil and the other station ary contact 126 is connected to the load terminal 1L to which the coil 6 is also connected at the other end.

The arrangement as above described is operated as follows: It is now assumed that an ON signal having the frequency of f is transmitted from a central control console (not shown) disposed at a substation (not shown) or the like through the associated power distribution line (not shown). Under the assumed condition. the ON signal reaching the source terminals and causes the resonance circuit 1 2 to resonate at the fre quency off This also causes the resonance of the resonator 3 because the latter has the natural frequency equal to that frequency of the signal being transmitted. Therefore the pickup coil 5 operatively coupled to the resonating resonator 3 develops by induction a voltage thereacross. Since the coil is connected across the gate and cathode electrode of the thyristor 7 through the movable arm of the switch I2 in its open position, the voltage induced across the coil 5 is applied to the gate electrode of the thyristor 7. When the resonator 3 reso nates at the frequency off the mating coil 5 is adapted to develop the very low voltage thereacross which is high enough to trigger the thyristor 7 to its conducting state. Therefore the thyristor 7 become conducting to permit an AC current from the source terminal 15 and 28 to flow through the diode 9 and capacitor I0 to rotate the motor I]. The switch 12 is arranged to respond to the rotational movement of the motor II through a predetermined angle to change from its open position as shown by solid line in FIG 1 to another or closed position as shown by dotted line. Thus as soon as the motor 11 has been rotated through the predetermined angle, the switch I2 is turned ON to connect the source terminal 25 to the load terminal 2L resulting in the energization of a load {not shown) connected across the load terminals ll. and 2L.

The switch I2 in its ON position also disconnects the pickup coil 5 from the gate-to-cathode circuit of the thyristor 7 to prevent the thyristor 7 from remaining in a conducting state even in the presence of the ON signal. Therefore the motor II is stopped. The capacitor I0 serves to interrupt a current flowing through the diode 9 when the thyristor 7 is not in its conducting state.

Next assuming that an OFF signal having the frequency off; is transmitted to the source terminals IS and 28, the resonance circuit I 2 resonates at that frequency off to vibrate the associated resonator 4 having its natural frequency equal to the frequency of f whereby a voltage is induced across the mating pickup coil 6 as in the coil 5. Because of the switch I2 in its ON position, the voltage thus induced brings the thyristor 7 in its conducting state to rotate the AC motor 11 in the same manner as above described in conjunction with the resonator 3. Immediately after the AC motor 11 has been rotated through a predetermined angle. the switch 12 is moved from its position as shown by dotted line in FIG. 1 to its normal position as shown at by solid line to be put in its OFF position. The switch 12 in its OFF position similarly disconnects the pickup coil 6 from the gate-to-cathode circuit of the thyristor 7 to put the thyristor in its non-conducting state resulting in the stoppage of the motor. At the same time the switch 12 is operated to disconnect the source terminal 25 from the load terminal 2L to deenergize the associ ated load.

Therefore the arrangement as shown in FIG. 1 is responsive to the ON and OFF signals alternatively and repeatedly transmitted from a central control console (not shown) through the associated power distribution line (not shown) across the source terminals 15 and 28 to be operated in the ON and OFF modes to permit the alternate energization and deenergization of a load (not shown) connected across the load terminals 1L and 2L In FIG. 2 wherein like reference numerals designate the components identical to those shown in FIG. I, there is illustrated a modification of the present invention including the AC motor provided with a self holding switch. A mechanical coupling from the AC motor 11 to the switch 12 as is schematically shown by broken line in FIG. 2 and will now be described with reference to FIG. 3.

As shown in FIG. 3, the AC motor 11 includes an output shaft 13 having first cam means 14 rigidly secured thereon. The cam means 14 includes a pair of cam plates 14a and 14b disposed adjacent to each other and actuating the movable arm 12a and the contact 1217 of the switch 12 respectively In FIG. 3, the movable arm I20 is shown as engaging the contact connected to the pickup coil 5 at the other end. The shaft 13 has mounted at the free end thereof a supporting disc 15 including an arcuate slot ISa. A second cam plate 16 is rotatably mounted on the end portion of the shaft 13 and controllably fixed to the supporting disc 15 through an adjusting screw 17 loosely extending through the slot 15a and acrew threaded into the cam plate 16. The cam plate 16 has its angular position relative to the supporting disc 15 controllable to any angular position within the region of the arcuate slot 15a The cam plate 16 is operativcly coupled to a normally open self-holding switch I8 preferably in the form of a microswitch through a lever 19. The self-holding switch 18 is maintained normally open and includes a stationary contact connected to the junction of the motor 11 and the capacitor 10 and a movable arm connected to the source terminal 25.

The arrangement of FIG. 2 is identical in the circuit configuration to that shown in FIG. I except for the self-holding switch 18.

As in the arrangement of FIG. 1, an ON signal with a frequency off applied across the source terminals and causes the thyristor 7 to conduct to rotate the motor 11 in the direction of the arrow shown in FIG. 3. At the end of the rotational movement of the motor 11 through a predetermined angle, the lever 19 disengages from the second cam plate 16 to bring the selfholding motor switch 18 into its closed position. The closure of the switch 19 causes the continuation of the rotational movement of the motor 11 regardless of whether or not a control signal that is the ON or OFF signal is present at the source terminals 18 and 28. It is to be noted that the control signal continues to be applied across the source terminals 18 and 28 only for a time interval up to the closure of the switch 18 plus a surplus time interval.

During a further rotational movement of the motor 11 and the output shaft 13, the movable arm 12a of the switch 12 falls upon an operating point a on the cam plate 14a to be engaged by the contact 12b. This causes the source terminal 18 to be connected to the load terminal 1L to permit the energization of a load connected across the load terminals 1L and 2L, such as an electrical water heater, although the load is not illus trated. Then the second cam plate 16 again engages the lever 19 to put the self-holding switch 18 into its open position. Therefore the motor 11 and accordingly the output shaft 13 is stopped.

The process as above described can be repeated with an OFF signal applied across the source terminals 18 and 28 except that the switch contact 12b falls upon an operating point b on the cam plate 14b to disengage from the movable arm 12a thereby deenergizing the load.

As in the arrangement of FIG. 1, the arrangement as shown in FIGS. 2 and 3 is responsive to the ON and OFF signals developed across the source terminals to control the associated load in the ON and OFF modes of operation.

If it is desired to operated a multiplicity of the arrangements such as shown in FIGS. 2 and 3 at different time points in the area of a particular substation, the angular position of the cam plate 16 relative to the supporting disc 15 may be changed from one to another arrangement by varying the position of the adjusting screw 17 along the slot 150 on the disc 15. For example, the adjusting screw 17 may be displaced from one end of the slot 150 (see FIG. 3) to an intermediate point on the slot 15a as illustrated in FIG. 4 wherein like reference numerals designate the components identical to those shown in FIG. 3. This measure causes the displacement of the angular positions of the operating points a and b on the cam plates 14a and b for actuating the switch 12 after rotation of the motor 11 has been initiated. Thus a time interval between the ap pearance of the ON or OFF signal across the source terminals 15 and 2S and the actuation of the switch 12 can readily be controlled.

The present invention has several advantages. For example, it is free from malfunction resulting from noise that may occur on the associated power distribution line because the switch 12 is operated after the motor has been rotated through a predetermined angle which is required to continuously apply the ON or OFF signal to the arrangement for a predetermined time interval. Also the present arrangement is reliable in operation with a simple construction because a pair of ON and OFF signals having different frequencies can put a switch in its ON and OFF positions respectively while a single switching circuit is used. Further. in the arrangement of FIGS. 2 and 4, a multiplicity of control receivers in the area of each substation can be suitably changed in operating time point thereby avoiding any abrupt change in the load of the substation with the result that a good quality of power can be supplied to customers.

While the present invention has been illustrated and described in conjunction with a few preferred embodiments thereof, it is to be understood that various changes and modification may be resorted to without departing from the spirit and scope of the invention.

What we claim is:

1. A control receiver comprising, in combination, a first electromagnetic coil responsive to a signal having a first predetermined frequency to provide an output voltage thereacross, a second electromagnetic coil rcsponsive to a signal having a second predetermined frequency different from said first frequency to produce an output voltage thereacross, a load circuit to be controlled, switch means connected in said load circuit and having an open position to open said load circuit and connect said first coil to said load circuit, and a closed operating position to close said load circuit and connect said second coil to said load circuit, a switching circuit connected to said first coil and said second coil and rendered conductive by the output from that coil connected by said switch means to the load circuit, and means responsive to the conduction of said switching circuit to change said switch means from one to the other of the open and closed positions.

2. A control receiver as claimed in claim 1, further comprising a signal responsive circuit responsive to the signal having either of said first and second predetermined frequencies to establish an oscillating magnetic field therein, first mechanical resonator means operatively coupled to both said signal responsive circuit and said first coil to respond to the magnetic field established in said circuit at said first frequency to cause said first coil to produce the output voltage across the latter through the vibration of said first resonator means and second mechanical resonator operatively coupled to both said resonance circuit and said second coil to respond to the magnetic field established in said signal responsive circuit circuit at said second frequency to cause said second coil to produce the output voltage across the latter through the vibration of said second resonator means.

3. A control receiver as claimed in claim 1, further comprising an electric motor driven during the conduction of said switching circuit, circuit means having a motor switch controlling the flow of electricity to said motor, first cam means rotated by said electric motor and having a predetermined rotational position for switching said switch means to said open position, and another predetermined rotational position for switching said switch means to said closed position, second cam means disposed for rotation with said first cam means and coactive with said motor switch and having a predetermined rotational position where said motor switch is opened to stop said electric motor, and means second cam means to said supporting member, and adjusting means for adjusting the relative position of said second cam means to said supporting means 

1. A control receiver comprising, in combination, a first electromagnetic coil responsive to a signal having a first predetermined frequency to provide an output voltage thereacross, a second electromagnetic coil responsive to a signal having a second predetermined frequency different from said first frequency to produce an output voltage thereacross, a load circuit to be controlled, switch means connected in said load ciRcuit and having an open position to open said load circuit and connect said first coil to said load circuit, and a closed operating position to close said load circuit and connect said second coil to said load circuit, a switching circuit connected to said first coil and said second coil and rendered conductive by the output from that coil connected by said switch means to the load circuit, and means responsive to the conduction of said switching circuit to change said switch means from one to the other of the open and closed positions.
 2. A control receiver as claimed in claim 1, further comprising a signal responsive circuit responsive to the signal having either of said first and second predetermined frequencies to establish an oscillating magnetic field therein, first mechanical resonator means operatively coupled to both said signal responsive circuit and said first coil to respond to the magnetic field established in said circuit at said first frequency to cause said first coil to produce the output voltage across the latter through the vibration of said first resonator means and second mechanical resonator operatively coupled to both said resonance circuit and said second coil to respond to the magnetic field established in said signal responsive circuit circuit at said second frequency to cause said second coil to produce the output voltage across the latter through the vibration of said second resonator means.
 3. A control receiver as claimed in claim 1, further comprising an electric motor driven during the conduction of said switching circuit, circuit means having a motor switch controlling the flow of electricity to said motor, first cam means rotated by said electric motor and having a predetermined rotational position for switching said switch means to said open position, and another predetermined rotational position for switching said switch means to said closed position, second cam means disposed for rotation with said first cam means and coactive with said motor switch and having a predetermined rotational position where said motor switch is opened to stop said electric motor, and means for adjusting the angular position of said second cam means relative to said first cam means.
 4. A control receiver device as claimed in claim 3, further comprising a supporting member rotated along with said first cam means, means adjustably fixing said second cam means to said supporting member, and adjusting means for adjusting the relative position of said second cam means to said supporting means. 